18. Shepherdess' movie role? : LEADING LADY. The star of the show; and a shepherdess is leading in a different sense. Ironically, Little Bo Peep didn't have that role.
39. Horse trainer's movie role? : BIT PART. A BIT is a piece of apparatus used by the trainer. It sits behind the teeth and is used to control the animal. Since BIT also refers to some small thing, a BIT PART is one filled by an actor who interacts with the main roles, but has five or fewer lines of dialog.
52. Weightlifter's movie role? : SUPPORTING ACTOR. This actor fills a role less important that that of the lead, but more filling than the BIT PART. The importance of this SUPPORT [see image below] is recognized by the separate awards [not pictured] granted in this category.
And the unifier --- 58. What 18-, 23-, 39- and 52-Across exemplify? : TYPE CASTING. This occurs when an actor repeatedly gets relegated to similar roles, and may have difficulty getting other types of roles. Incredibly, this list omits Sean Bean, always a failed near-hero who meets a violent end.
Alas, poor Sean - not for the faint-hearted - and they missed Boromir
Hi gang, it's JazzBumpa cast in the role of usher, to lead you through this theatrical blockbuster. Just have a seat here and we'll get the roles rolling.
Across
1. Mutinous Kubrick computer : HAL. A SUPPORTING ROLE in 2001, A Space Odyssey.
4. High-end violin : STRAD. Short for STRADivarius, any string instrument made by various members of the STRADivarius family, particularly Antonio, during the 17th and 18th centuries. AMATI also fits.
9. Sextet for Henry VIII : WIVES. Henry had six wives. A sextet - oh, my.
14. British verb suffix : ISE. We Americanize, They Anglicise [though spell check disagrees.]
15. "Some glory in __ birth ...": Shak. : THEIR. From Shakespeare's Sonnet 91.
16. Ginsburg associate : ALITO. Justices of the U.S. Supreme Court.
17. Sprightly dance : JIG.
20. Sharp-wittedness : ACUMEN. The ability to make quick judgments and good decisions.
22. Gore, once : VEEP. Al was the Vice President at the end of the previous century. He was not related to Leslie, who passed away on 2/16/15. RIP songstress.
29. Met previously : KNEW. I knew I knew you.
30. "I'm listening ..." : GO ON. Keep talking
31. Delta deposit : SILT. Fine granular high silica material suspended in river water then deposited at the river mouth.
32. False flattery : SMARM. Insincere ingratiating behavior.
34. Robbins' ice cream partner : BASKIN.
36. ER personnel : M.D.s. Medical Doctors in the emergency room.
41. Org. concerned with the AQI : EPA. Environmental Protection Agency and the Air Quality Index
42. Crankcase component : OIL PAN. The bottom section of the crankcase acting as a reservoir for the engine oil.
44. Sends out : EMITS.
46. Boyfriend : BEAU.
47. Bearing : MIEN. A person's physical demeanor, especially as it relates to attitude and personality.
48. Meat pkg. letters : USDA. U. S. Dept. of Agriculture stamp on meat packaging.
56. Chamber group often including a piano : TRIO. An ensemble of three instruments.
6 min: 20 sec
57. Under control : IN HAND. Like a violin.
63. Loafer front : TOE. Shoe part
64. Madison Square Garden, e.g. : ARENA. Sports venue.
65. Cookbook verb : SAUTE. I'm not sure how this differs from frying.
66. Decorative vase : URN.
67. H.S. hurdles : PSATs. Pre-SATs. S.A.T. originally stood for Scholastic Aptitude Test, but in 1990, when it became obvious that it was no such thing, the name was changed to SAT, which evidently stands for nothing. Just one more educational scam? You decide.
68. Heavy metal cover : ARMOR. Medieval personal protection gear, not a rerecording of Led Zeppelin Hits.
Another 6 minutes well spent
Down
1. Take by force : HIJACK. Usually the thing taken is a vehicle of some sort.
2. "... based on my abilities" : AS I CAN. Is this an in the language phrase?
3. Peanut, for one : LEGUME. A dry dehiscent one-celled fruit developed from a simple superior ovary and usually dehiscing into two valves with the seeds attached to the ventral suture. If that seems a bit obscure, just think about peas and beans.
4. Fifth cen. pope called "The Great" : ST. LEO. He negotiated with Attila the Hun at the gates of Rome and persuaded the Vandals not to pillage the city, which actually is pretty great.
5. "Come to think of it ..." : THEN AGAIN.
6. Stephen of "Breakfast on Pluto" : REA.
7. Succor : AID. And comfort.
8. Hungry for success, say : DRIVEN. Type A personality.
9. Track transaction : WAGER. You want to bet? Or are you just horsing around?
10. "No thanks" : I'LL PASS. Me too. I'm not a gambler.
11. Google Maps directions word : VIA. By means of a particular route.
12. Sea-Tac approx. : E.T.D. Seattle-Tacoma International Airport and Estimated Time of Departure. Yes, this sent me agoogling.
13. Protein-rich bean : SOY. Another LEGUME.
19. Org. that funds cultural exhibitions : N. E. A. National Endowment for the Arts.
21. Litter peeps : MEWS. Kitty litter - no, wait . . .
24. Cruise stop : PORT.
25. Italian archaeological attraction : POMPEII. City annihilated by the eruption of Mt. Vesuvius in 79 AD.
26. Puma competitor : NIKE. Athletic shoes.
27. Paper holder : CLIP.
28. Italian tourist attraction : ETNA. Another Italian volcano.
33. CFO's degree : M.B.A. Masters in Business Administration.
34. Invite as a member of : BRING INTO.
35. Verizon competitor : A.T.T. Once upon a time, American Telephone and Telegraph.
36. Unruly groups : MOBS.
37. The Lord, in Lourdes : DIEU. French for God.
38. Response to freshness? : SLAP.
40. "You got that right!" : AMEN.
43. Campsite sight : PUP TENT.
45. Very : SUCH. As in "of such importance . . ." Still, a clumsy fit.
47. Peak near Olympus : MT. OSSA. Not to be confused with the one in Tasmania.
49. Lincoln Memorial feature : STATUE.
50. Bloodmobile visitors : DONORS. Not vampires.
51. Zealous : ARDENT.
53. Black-and-white sea predators : ORCAS. Killer whales
54. Narrow inlet : RIA. A coastal inlet formed by the partial submergence of an unglaciated river valley. It is a drowned river valley that remains open to the sea.
55. __ management : ANGER. For those with hostility issues.
58. Bug on the line : TAP. Eavesdropping equipment, not insects.
59. Timeline parts: Abbr. : YRs. Years.
60. Shooter lead-in : PEA. A PEA shooter is a blow gun for propelling small objects, such as peas. By extension, any small bore weapon or trombone.
61. Sealing goo : TAR. For roads or roofs.
62. Periodic table suffix : IUM. As in helIUM.
69. Del. clock setting : E.S.T. Eastern Standard Time in Delaware.
OK, folks. That draws the curtain on the final scene. Among other things, we visited outer space, had mountainous terrain and a number of musical interludes. I'll give this production two thumbs up. How about you?
Cool Regards!
JzB